Cavity resonator construction or the like



June 9, 1959 N. J. REGNIER 2,890,425

CAVITY RESONATOR conswaucnou OR THE 1.1m:-

Filed April 30, 1957 2 Sheets-Sheet 1 wommn/ REG/VIE)? INVENTOR.

HIS ATTORNEY N. J. REGNIER CAVITY RESONATOR CONSTRUCTION OR THE LIKE Filed April :50, 1957 June 9, 1959 2 Sheets-Sheet 2 E/////////////////////////A/g/// /fiA//7/// 4 .K

E Ev//v////// m m FIG. 2

NORMAN J. RE'GW/E'R INVENTOR. M

H/S ATTORNEY CAVITY RESONATOR CONSTRUCTION OR THE LIKE Norman J. Regnier, Los Angeles,"Calif.,-assignorto Holiman Electronics Corporation, a corporation of- California Application April 30,1957, Serial No. 656,105

3 Claims. (Cl.' 333-82) This invention is relatedtocavity-resonators in general and, rnore particularly, to a new and improved-cavity resonator construction which will exhibit a-highdeg-ree of compactness relative to operating frequencies thereof.

In many types of military andcommercial applications, it has been found to-be undesirable to incorporateconventional, coaxial, cavity resonators inelectronic circuits or systems having operating frequencies in the region of the upper portion of the VHF band and the lower portion of the UHF frequency band, owing to the physically cumbersome size and weight of conventional, quarter-wave resonant, cavity resonators. It wouldof course be highly desirable to achieve a cavity resonator construction which will exhibit compactness, particula'rlyin height, so that quarter-wave resonance -may be achieved by. a cavity resonator without necessitating the physicalhei'ght thereof to approach a quarter-wave lengthin physical measurement.

Accordingly, it is anobject ofthepresent'invention' to provide a new and useful cavity resonator construction.

It is a furtherobject of the-present invention to provide a new and useful cavity resonator construction which will exhibit optimum compactness relativeto frequencies of operation.

It is an additional object of the present invention to provide a new and usefulcavity resonator construction of a doubled-back configuration which willbe selectively tunable byactuation;of:-aa simplegtidiustment device.

According to the present invention,. a coaxial ,or reentrant type cavity resonator is provided with acentral, tubular portion, and, cooperating with'the same, a rodlike portion attached to or integral with a top member cooperating with the cavity resonator proper. Accordingly, the quarter-Wave resonance distance will be measured from the ground plane or base of the cavity resonator, up to the top thereof, and doubled back through the central tubular portion of the cavity resonator to the termination of the rod member or portion disposed within the aforementioned tubular portion of the cavity resonator. Thus, for a slight increase in diameter, the cavity resonator of the present invention will exhibit an overall physical height which will be slightly more than or equal to one-half of that fraction of wavelength at which the cavity resonator is to be resonated.

The features of the present invention which are believed to be novel are set forth with particularity in the appended claims. The present invention, both as to its organization and manner of operation, together with further objects and advantages thereof, may best be understood by reference to the following description, taken in connection with the accompanying drawings, in which,

Figure l is an exploded view, partially in cross-section, of the cavity resonator construction of the present invention.

Figure 2 is a front sectional view of the apparatus of Figure 1.

In Figure 1, cavity member includes outer tubular portion 11 having first and second end portions 12 and portion 14 and also within dielectric member 18.

Fatented June 9, 1959 single, unitary,- cavity member. A suitable material employable in the fabrication of cavity member 10 would be either silver or a silver coated material such as brass,'with 'the base portion 17 being silver-soldered to outer tubular portion 11 and inner tubular portion 14, should the same initially comprise separate parts. In this latter event, it may well be both appropriate and necessary to provide internal and external recesses, respectively, at .the first end portions of outer tubularportion 11 and inner tubular portion medals to provide appropriate seats for the mounting of these respective .parts to base portion 17.

The energy coupling means for the cavity are not shown in Figure 1, for purposes of clarity, but rather are illus trated in Figure 2.

Disposed within inner tubular portion 14 isdielectric member 18. Afiixed to dielectric member 18 is externally threaded set screw 19 which is provided with a portion 26 adapted to seat, with the incorporation of suitable adhesive means, dielectric member 18 to set screw or screw means 19.

The interior-ofinner tubular portion 14 has a threaded area 21 which is adapted to receive setscrew 1%. Threadedarea 21 of internal tubular portion 14 is also adapted to receive locking screw 22, which itself is adapted forcooperation With-the lower surface of set screw'19. Top member '23 of the cavity resonator includes top portion 24 and also rod'portion 25. Rod portion 25 is adapted for. disposition'within inner tubular It should be mentioned in passing that dielectric member 18 may be composed of nylon, Teflon, or of a ceramic material, in fact, any material which exhibits a high dielectric constant and low loss characteristics. Top member 23 may be either cast as'a single unitary'member, ormay be fabricated by separate members composing the top portion 24 and rod portion 25. In the latter event, the upper end of the rod portion 25 should be shouldered and also an aperture suitably provided in top portion 24 so as to provide for the cooperation, by silversolder means for example, of rod portion 25 with top portion 24.

It is to be noted that top portion 24 of top member 23 is lid-shaped and is selectively adapted for cooperation with the outer annular recessed area 26 of cavity member 10.

Circular indentations 27 may be provided on either side of cavity member 10 so as to accommodate the placement therewithin of the end portions 28 of retaining element 29, preferably made of spring steel.

In Figure 2 there is illustrated in cross-section the cavity resonator construction of Figure 1. It is to be noted that a detent recess area 200 may be provided at the top of top member 23 so as to accommodate the selective placement therewithin of detent portion 2% associated with retaining element 29. The purpose of course for the inclusion of retaining element 29 is to retain selectively top member 23 of the cavity resonator construction against cavity member 10 of the construction.

There is also shown in Figure 2 the inclusion in the construction of input and output probes 202 and 203. One end of these probes may be soldered or otherwise affixed to appropriate points along the inner wall of outer tubular portion 11; the remaining ends 204 and 205 of the probes may be adapted for coupling to input and output circuits associated with the cavity resonator construction (not shown). It will of course be understood by those skilled in the art that the particular points along the inner wall of outer tubular portion 11 at which the probes will be affixed will be determined by the impedance matching characteristic desired. Apertures 206 may be provided in the wall of outer tubular portion 11 so as to accommodate the positioning of input and output probes 202 and 203. The aforementioned probes may be insulated from the wall of outer tubular portion 11 by means of insulating grommets 207 and 208, as shown.

The apparatus shown in Figures 1 and 2 is assembled and operates as follows, The cavity resonator construction is assembled by positioning rod portion 25 within inner tubular portion 14 and dielectric member 18, which are associated with cavity member 10. The top member 23 is fixedly retained to cavity member 10 by the upright positioning of retaining element 29. The cavity resonator apparatus is tuned by removing the locking screw 22 (see Figure 2, for example), by rotating appropriately screw 19, so as to advance inwardly or outwardly as desired dielectric member 18. This advancement or withdrawal of dielectric member 18 afiEects the capacitance between rod portion 25 and inner tubular portion 14, and this effect will result in a change in resonant frequency of the cavity resonator construction. The locking screw 22, thus, need only be replaced and rotated so as to come in contact with the lower surface of locking screw 19, thus to lock in position the dielectric member 18 relative to rod portion 25, of top member 23, and inner tubular portion 14.

It is to be noted in Figure 2 that by virtue of the doubling-back physical construction of the cavity resonator of the present invention, that quarter-wave resonance of the cavity resonator, for example, may be achieved by a device which is slightly more than one-half as high, physically, as the corresponding electrical length or fraction thereof at which the cavity resonator is operating.

The present invention his proven highly satisfactory during testing operations, offering relatively good open circuit Qs approximating 1500 to 2000 and loaded Qs, depending upon impedance match, of 500 to 800.

The present invention is ideally suited for incorpora- 4 tion within compact UHF or VHF equipment in which the physical size of cavity resonator units is a chief consideration.

While particular embodiments of the present invention have been shown and described, it will be obvious to those skilled in the art that changes and modifications may be made without departing from this invention in its broader aspects, and, therefore, the aim in the appended claims is to cover all such changes and modifications as fall within the true spirit and scope of this invention.

I claim:

1. A cavity resonator including, in combination, a cavity member having an outer tubular portion provided with first and second end portions, an inner tubular portion provided with first and second end portions, and a base portion integral with said first end portions of said outer and inner tubular portions; a top member having a top portion cooperating with said second end portion of said outer tubular portion, but spacially removed from said second end portion of said inner tubular portion, and a rod portion provided with an end portion integral with said top portion and a principal portion disposed substantially within but physically separated from said inner tubular portion of said cavity member; translationally displaceable dielectric means disposed at least in part between at least portions of said inner tubular portion of said cavity member and said rod portion of said top member; means for coupling energy into said cavity resonator; and means for withdrawing energy from said cavity resonator.

2. Apparatus according to claim 1 in which said inner tubular portion is provided with an internally threaded area in the region of said first end portion thereof, and in which screw means is affixed to said dielectric means, said screw means being disposed for travel within said threaded area of said inner tubular portion of said cavity member.

3. Apparatus according to claim 2 in which there is provided an additional screw means within said threaded area of said inner tubular portion, of said cavity member, for locking the former screw means in a chosen disposition.

References Cited in the file of this patent UNITED STATES PATENTS 

